Cooling element for refrigerating systems



p 1934- R. s; TAYLOR COOLING ELEMENT FOR REFRIGERATING SYSTEMS FiledDec. 2, 1932 s Sheets-Sheet 1" INVENTOR.

ATTORNEY. I

Jul; 5

Sept. 11, 1934.

R. s. TAYLOR COOLING ELEMENT FOR REFRIGERATING SYSTEMS Filed Dec. 2.1932 3 Sheets-Sheet 2 a l l I, l I

1N VEN TOR. 5-

ATTORNEY.

Sept. 11, 1934. I R s TAYLOR 1,973,127

COOLING ELEMENT FOR REFRIGERATING SYSTEMS Filed Dec. 2, 1932Sheets-Sheet 3 C ,in

I ATTORNEY.

a Z5 n i INVENTOR.

Patented Sept. 11, 1934 UNITED STATES COOLING ELEMENT FOR REFRIGERATINGSYSTEMS Robert S. Taylor, Evansville, Ind., assignor to ElectroluxServel Corporation, New York, N. Y., a corporation of DelawareApplication December 2, 1932, ser al No. 645,431

9 Claims.

My invention relates to refrigeration and more particularly to a new andimproved cooling element for a system which produces refrigeration bythe evaporation of liquid cooling fluid by diffusion into an inertauxiliary gas.

In household type refrigerators it is usually necessary that the coolingelement provide a low temperature chamber for making ice or the like andalso a suflicient amount of heat transfer surface for cooling air in thestorage compartment to a temperature suitable for the properpreservation of comestibles.

Further, the cooling element should be of the smallest size possible foradequate freezing of ice cubes and cooling the air in the storagecompartment in order to allow the greatest possible amount of foodstorage space.

In refrigerating systems of the pressure equalized absorption type forhousehold service the evaporator heretofore used comprises a closedvessel having a plurality of liquid spreading bafiles. Liquid coolingfiuid such as ammonia introduced into the upper part of the evaporatorfiows downwardly over the bafiles evaporating into an inert gas such ashydrogen circulated through the evaporator. In order to provide forfreezing ice cubes and cooling the storage compartment, a trayreceptacle of thermal conductive material such as cast aluminum, issecured to the evaporator, this receptacle being provided exteriorlywith extensive heat transfer Surface such as integrally cast fins.

In accordance with my invention there is provided a cooling element forsuch a refrigerating system which is compact and provides a thermallyisolated freezing compartment for ice trays and adequate heat transfersurface for cooling the air in the storage compartment. My coolingelement comprises a pipe coil evaporator generally of the type disclosedin Patent No. 1,729,625 to Carl G. Munters but arranged with loopssurrounding an open front freezing area such as disclosed in anapplication Serial No. 645,422 by Sven W. E. Andersson and W. R.Hainsworth, assigned to the same assignee as the-present invention, andprovided with a sheet metal structure forming highly thermal conductiveice tray supports or shelveswithin the freezing area surrounded by a lowthermal conductive shield having extensive exterior heat transfersurfaces. My invention will be more readily understood from thefollowing description taken in connection with the accompanyingdrawings, in which, Fig. 1 is a sideelevation of a cooling elementcontemplated by my invention;

7 Fig. 2, a front end view of the cooling element shown in Fig. 1; 1Fig. 3, a plan view of the cooling element shown in Figs. 1 and 2;

refrigerating system for the circulation of an.

inert auxiliary gas such as hydrogen through the coil. A liquid coolingfluid such as ammonia is conducted into the upper end of the coilthrough conduit, 13 which is shown extending concentrically within theupper end 11 of the coil. As best shown in Fig. 2, the coil 10 has aconstantly downward slant such that the liquid cooling fluid introducedat the upper end will have a continuously downward path of flowtherethrough. Within the coil I preferably provide means for retainingthe liquid in a manner to present an extensive surface, for instance awick-like lining 23 (see Fig. 5) which distributes the liquid in finelydivided form over the'interior surface of the coil by capillarity, asdisclosed in the abovementioned application of Andersson et a1. Whenammonia is used as the cooling fluid the coil 10 is preferably of steeltubing and the lining of steel mesh or the like. 'As shown in Fig. 2 theturns of the coil may be positioned by spacing bars 14 welded betweenthe front ends of the loops and, as shown in dotted outline in Fig. 1,by spacer bars 15 welded between the rear loops.

Shelves or tray supports 16 are formed by sheets of copper or other goodthermal conductive material extending horizontally between substantiallyopposite leg portions of the U-bends, the outer edges of the sheetsbeing bent over the coil and soldered, brazed, or welded in good thermalcontact. The freezing area defined by the coil 10 is enclosed, except atthe front, by a side wall formed by a. sheet 1'7 of galvanized iron orother poorer thermal conductive material bent around the outside of thecoil 10 and a top cover sheet 18 secured around-its edges to the topedge of the side wall sheet 17.- On the outside of the side wall sheet17 are mounted grid structures formed by sheets 19 and 20 also of ironor other relatively low thermal conductive material having portionsstruck outwardly therefrom to form heat transfer fins 21. The side wall17 and grid structures 19 and 20 are conveniently secured in positionaround the coil 10 by lugs. or fiaps 22 struck out of the turned-overedges of the shelves 16 extending through slots in the sheet metal walland over-turned on the outside.

A cooling element constructed as described above is characterized byhigh heat conductivity and relatively small surface for freezing waterin the ice trays, and by a large surface of relatively low heatconductivity for cooling air in the box. In cooling the air in thestorage compartment, a large surface for heat transfer is necessarybecause the greatest temperature drop is between the air and thissurface. However, the conductivity between the transfer surface and theevaporator coils need not be very great because the amount of heattransfer per unit of surface is. relatively small wherefore theenclosing wall and grid structure described above is made of lowconductivity metal such as galvanized iron or some similar materialwhich will not rust. The

low conductivity metal enclosure also acts as ashield and preventsconduction of heat fromthe cabinet to the ice trays, thus decreasingthe'freezing time. .The shield also prevents circulation of air in thefreezing chamben'thus reducing the condensation and freezing of moisturearound the tinuously downward flow of liquid therethrough,

said coil comprising a plurality of substantially horizontal superposedU-shaped turns, means within said coil for retaining liquid in finelydivided form over an extensive surface, a connection for liquid coolingfluid to the upper end of said coil, highly thermal conductive supportsfor containers of substance to be frozen within the space outlined bysaid coil and attached thereto, and a shield of low thermal conductivematerial around said coil.

2. A cooling element comprising a pipe coil adapted for circulation ofinert gas and continuously downward flow of liquid therethrough, saidcoil comprising a plurality of substantially horizontal superposedU-shaped turns, means within said coil for retaining liquid in finelydivided form over an extensive surface, a connection for liquid coolingfluid to the upper end of said coil, highly thermal conductive sheetmetal plates extending between and mounted on opposite legs of saidturns, and a shield of low thermal conductive sheet material around saidcoil.

3. A cooling element comprising a pipe coil adapted for circulation ofinert gas and continuously downward flow of liquid therethrough, saidcoil comprising a plurality of substantially horizontal superposedU-shaped turns defining a freezing space open at one end, means withinsaid -coil for retaining liquid in finely divided form overan extensivesurface, a connection for liquid cooling fluid to the upper end of saidcoil, and a casing of low heat conductivity around said coil, saidcasing having an aperture at the open end of said freezing space and anextensive heat transconduit comprising a plurality of substantially,

horizontal superposed U-s haped turns, means within said coil forretaining liquid in a manner to present extensive surface area of theliquid to the gas, a connection for liquid cooling fluid to the upperend of said coil, supports formed by sheets of highly thermal conductivemetal extending between and attached to opposite legs of said turns, ametal casing of low thermal conductivity around said coil forming afreezing chamber open at the open ends of said turns, and a plurality ofheat transfer fins on the outside of said casing.

5. A cooling element comprising a steel pipe coil adapted forcirculation of inert gas and continuously downward flow of liquidtherethrough, said coil comprising a plurality of substantiallyhorizontal superposed U-shaped turns, means within said coil for.retaining-liquid in a manner to present extensive surface area ofthe'liquid' to the gas', a= connection for-liquid cooling fluid to theupper end of said coil, horizontal-shelves formed by sheets of copperextending between i and attached to opposite legs of said turns, and acasing of galvanized sheet iron around said coil forming afreezing'chamber open at the open ends of said turns, said casing havingextensive exterior heat'transfer surfaces. i

6. A cooling element comprising a steel pipe coil adapted forcirculation of inert gas and continuously downward flow of liquidtherethrough,

said coil comprising a plurality of substantially horizontal superposedU-shaped turns, means within said coil for retaining liquid in a mannerto present extensive surface area of the liquid to the gas, aconnection'for liquid cooling fluid to the upper end ofsaid coil,shelves formed by sheets of copper extending between and bent downwardlyover the outside of opposite legs of said turns, said sheets having tabsstruck outwardly from the down-turned portions, and a casing ofgalvanized sheet iron around said coil forming a freezing chamber openat the open end of said turns, said casing being provided with heattransfer flns and having slots through which said tabs extend forsecuring said casing.

'7. A cooling element comprising a pipe coil adapted for circulation ofinert gas and continuously downward flow of liquid therethrough, saidcoil having vertical rows of substantially parallel horizontal portions,supports formed by sheets of highly thermal conductive metal extendingbetween and attached to horizontally opposite, portions of said coil,and a metal casing around said coil and secured to said support-formingsheets.

8. A cooling element comprising a pipe coil having a plurality ofsuperposed U-shape turns, supports formed by sheets of thermalconductive metal extending between and attached to opposite legs of saidturns, and a metal casing around said coil forming a freezing chamberopen at the front ends of said turns and secured in place by tabs struckout from said support-forming sheets.

, 9. A cooling element comprising a pipe coil having a plurality ofsubstantially horizontal superthermal conductive metal extending betweenand bent downwardly over opposite legs of said turns, said sheets havingtabs struck outwardly from the down-turned portions, and a casing of lowthermal conductive material around said coil provided with heat transferfins and having slots through which said tabs extend for securing thecasing.

ROBERT S; TAYLOR;

